In order to maintain security in a network such as a home automation system, the admission of devices into the network is controlled. This typically involves either imparting network access information from the network to the device to be admitted, or conveying information from the device to the network. Since it is very difficult to confine radio communications to a physically secure area, exchanges of private information can be subject eavesdropping, man-in-the-middle, and replay attacks. In order to prevent this, encryption is commonly used to protect the information sent over the radio channel. Establishing encrypted communication requires some form of cryptographic key exchange between the participants. This can be done either over the radio channel itself, or by some independent means. To exchange keys securely over an unsecured channel requires a secure key exchange algorithm such as Diffie-Hellman-Merkle Key Exchange. These algorithms typically place a burden on very simple network nodes, such as light switches, light bulbs, and so forth, that is unacceptable in terms of computational and/or energy resources. Several mechanisms have been considered for conveying commissioning information to or from devices without the use of radio links. For example, the user can manually enter data printed on the device or its packaging into a network control device, the data exchange can be confined to a small period of time initiated by some user action (e.g., pressing a button), or a camera on a smart phone or tablet can be used to scan and decode codes printed on the device or its packaging, such as linear bar codes and two dimensional codes such as quick response (QR) and DataMatrix codes.